Plant Physiological Ecology
Language: English
Pages: 605
ISBN: 0387783407
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Box 9E. 1 Continued FIGURE 2. The C–S–R triangle model (Grime 1979). The strategies at the three corners are C, competiti- winning species; S, stress-tolerating s- cies; R,ruderalspecies. Particular species can engage in any mixture of these three primary strategies, and the m- ture is described by their position within the triangle. comment briefly on some other dimensions that Grime’s (1977) triangle (Fig. 2) (see also Sects. 6. 1 are not yet so well understood. and 6. 3 of Chapter 7 on growth and allocation) is a two-dimensional scheme. A C―S axis (Com- tition-winning species to Stress-tolerating spe- Leaf Economics Spectrum cies) reflects adaptation to favorable vs. unfavorable sites for plant growth, and an R- Five traits that are coordinated across species are axis (Ruderal species) reflects adaptation to leaf mass per area (LMA), leaf life-span, leaf N disturbance. concentration, and potential photosynthesis and dark respiration on a mass basis. In the five-trait Trait-Dimensions space,79%ofallvariation worldwideliesalonga single main axis (Fig. 33 of Chapter 2A on photo- A recent trend in plant strategy thinking has synthesis; Wright et al. 2004). Species with low been trait-dimensions, that is, spectra of varia- LMA tend to have short leaf life-spans, high leaf tion with respect to measurable traits. Compared nutrient concentrations, and high potential rates of mass-based photosynthesis. These species with category schemes, such as Raunkiaer’s, trait occur at the ‘‘quick-return’’ end of the leaf e- dimensions have the merit of capturing cont- nomics spectrum.
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And Long Distance Transport FIGURE 5. Phloem-loading pathways and mechanisms. (A) Apoplastic loading. Sucrose from mesophyll cells (M) diffuses through plasmodesmata to bundle sheath cells (BS) and into the minor veins. Inside the veins, it enters the cell-wall space (apoplast, in grey) near the phloem, and is loaded into the companion cells (CC) and/or sieve elements (SE) by secondary active transport. A sucrose transporter is shown as a star. Phloem parenchyma cells (not shown) are part of the.
Sun and shade leaves and due to free air ozone fumigation. Environ. Exp. Bot. 59: 130 138. Weger, H.G., Silim, S.N., & Guy, R.D. 1993. Photosynthetic acclimation to low temperature by western red cedar seedlings. Plant Cell Environ. 16: 711 717. Weston, D.J., Bauerle, W.L., Swire Clark, G.A., Moore, Bd., & Baird, W.V. 2007. Characterization of Rubisco activase from thermally contrasting genotypes of Acer rubrum (Aceraceae). Am. J. Bot. 94: 926 934. Winter, K. & Smith, J.A.C. 1996. An introduction.
Compounds, RQ is close to unity, whereas for the fat storing seeds of Linum usitatissimum (flax) RQ values as low as 0.4 are found (Stiles & Leach 1936). Both the nature of the respiratory substrate and biosynthetic reactions strongly influence RQ. The RQ can be greater than 1, if organic acids are an important substrate, because these are more oxi dized than sucrose, and, therefore, produce more CO2 per unit O2. On the other hand, RQ will be less than 1, if compounds that are more reduced than.
Pneumatophores of mangroves, lenticels in the bark of many wetland trees, and, possibly, the knee roots of Taxodium distichum (bald cypress). The mechanisms that maintain the intercellular spaces filled with gas rather than water are not fully under stood. Inward radial gradients in water potential created by transpiration in combination with water impermeable apoplastic barriers such as the exodermis may offer an explanation (Jackson & Armstrong 1999). Because there is a gradient in partial.
Copyright Elsevier Science, Ltd.). respective growth temperatures; however, complete homeostasis is uncommon. Acclimation can play an important role in weakening positive feedback through the warming respiration atmospheric CO2 concentration connection (Atkin & Tjoelker 2003). Acclimation of leaf respiration to temperature is lar ger in conifers than in broad leaved species (Tjoelker et al. 1999); other than that, there are no major sys tematic differences in the degree of acclimation among.